Verify fast symlink length stored in inode->i_size matches the string
stored in the inode to avoid surprises from corrupted filesystems.
Reported-by: syzbot+48a99e426f29859818c0@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: bae80473f7b0 ("ext4: use inode_set_cached_link()")
Suggested-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/ext4/inode.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7c54ae5fcbd4..fbda5a67f7f9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5007,8 +5007,16 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
inode->i_op = &ext4_encrypted_symlink_inode_operations;
} else if (ext4_inode_is_fast_symlink(inode)) {
inode->i_op = &ext4_fast_symlink_inode_operations;
- nd_terminate_link(ei->i_data, inode->i_size,
- sizeof(ei->i_data) - 1);
+ if (inode->i_size == 0 ||
+ inode->i_size >= EXT4_N_BLOCKS * 4 ||
+ strnlen((char *)ei->i_data, inode->i_size + 1) !=
+ inode->i_size) {
+ ext4_error_inode(inode, function, line, 0,
+ "invalid fast symlink length %llu",
+ (unsigned long long)inode->i_size);
+ ret = -EFSCORRUPTED;
+ goto bad_inode;
+ }
inode_set_cached_link(inode, (char *)ei->i_data,
inode->i_size);
} else {
--
2.43.0
--rbk7j4upftqdugse--
